In order to protect traffic services within a computer network, service providers often deploy one or more “fast reroute” (FRR) techniques in order to quickly respond to link, node, and SRLG (shared risk link group) failures. For example, Multi-Protocol Label Switching (MPLS) provides for Traffic Engineering (MPLS-TE) techniques that may be used to offer FRR protection. In order for FRR to be effective, failures must be detected quickly. For instance, link failures may be detected using various connectivity verification protocols, such as hardware based alarms (e.g., synchronous optical network, “SONET”, or synchronous digital hierarchy, “SDH” alarms) or by using a message-based (e.g., “hello” packet) protocol such as bi-directional forwarding detection (BFD).
Those skilled in the art will appreciate that node failures are undoubtedly more difficult to detect than link failures, especially when the node failure does not imply a failure of its local links. In particular, certain types of node failures cannot be detected using local failure detection techniques for which an end-to-end hello-based mechanism is required, such as dataplane issues (e.g., forwarding tables having a corrupted entry, backplane issues, etc.) of traffic forwarded on tunnels available through MPLS TE (e.g., label switched paths, or LSPs). These types of node failures may only be detected if hello packets are sent onto the tunnel itself, conventionally over a connectivity verification protocol session (e.g., BFD session) established end-to-end between a head-end node and a tail-end node of the tunnel. However, when an end-to-end tunnel connectivity verification protocol session learns of a failure, the entire end-to-end topology of the tunnel is removed or “pruned” due to the inability to more precisely locate the failure.